Current lie detection methods, based on the polygraph technique, rely upon the measurement of several physiological characteristics to discriminate whether a truth or a lie is expressed. These measurements include skin resistivity, blood pressure, heart rate and respiration rate.
The most commonly employed procedure in criminal investigation is the Control Question Technique (CQT) used for formulating questionnaires. In this procedure, three types of questions are included: relevant (e.g., Did you rob the bank on March 2?), irrelevant (e.g., Did you graduate from high school?) and control (e.g., Have you ever stolen anything?). The control questions are designed to elicit an emotional response in innocent subjects that exceeds the response to the relevant questions. Relevant questions are designed to elicit large emotional response in guilty subjects. The role of the examiner is to formulate the questions and to interpret the results. Another approach, the Guilty Knowledge Test (GKT) presents the subject with information known to him but unknown to the public. The subject is asked relevant questions and control questions. Relevant questions contain information about the crime designed to arouse the subject if he is guilty, and control questions are designed to arouse him if he is innocent. This procedure relies on the assumption that autonomic arousal is induced in the guilty subject by aspects of the transgressive act and situation known only to him.
These methods describe above require the availability of a polygraph machine and the presence of qualified personnel to wire up the subject, and administer and interpret the test.
Direct electro-encephalographic (EEG) measurements of event-related brain potentials (ERP) to particular questions or situations, can also be used. ERP components relevant to lie detection are the endogenous components representing brain processing that occur after the earliest, sensory driven, exogenous components die down. Researchers have used the amplitude of endogenous components, notably P300 and N400, in lie detection studies Bashore 77!. Thus brain potential studies have demonstrated the existence of larger amplitude delayed responses in deception situations.
These techniques, still experimental, also require, like classical polygraphy, the availability of ERP machines and of competent personnel to wire test subjects and to interpret results.
State of the art lie detection methods rely on specialized equipment and highly trained personnel to administer tests. While advances in brain monitoring technology provides opportunities for more precise tests using expensive equipment such as EEG, there is a need for simple, easy to use, accessible and reliable devices that can be used locally or at a distance, without having to wire up the subject. Benefiting organizations would include the FBI, CIA, Armed Services, IRS, as well as drug testing programs, educational institutions and public sector businesses such as credit card companies and banks.
This invention is justified by the experimentally observed fact that endogenous components of brain activity can be delayed with increased brain processing Bashore 93!, and Ritter, Simson and Vaughan! and Kutas et al, 1977!. Significant delays in electro-encephalographic response time (RT) have also been observed in response to increased brain processing Kutas et al, 1977!. Farwell et al 8!, in particular, shows that event-related brain potentials can be used in interrogative polygraphy. In U.S. Pat. Nos. 5,467,777, 5,406,956 and 5,363,858 Farwell describes lie detection methods using electro-encephalography. In U.S. Pat. No. 5,170,780 Rosenfeld uses electro-encephalography to measure the P3 brain wave to perform lie detection.
It is an object of this invention to provide a simple yet effective lie detection system based on time measurements of voluntary physical motor responses, such as manual or vocal reaction times, and a judiciously chosen questionnaire composition methodology.
It is another object of the invention to provide a lie detection method that does not require having to wire up the test subject.
It is another object of this invention to provide a computerized and objective means of analyzing the data thus facilitating the task of the operator and providing for greater objectivity, uniformity, consistency and reliability of the test results, independently of the skill or interpretation of the operator.
It is yet another object of this invention to provide a lie detection tests that can be administered locally, or at a distance. For example the subject could be responding through a keyboard to written questions sent to him through a radio or telecommunication link. Remote operation could also be in audio form in which the subject hears a question on a telephone and must answer it orally using a simple response such as "yes" or "no".
It is yet another objective to provide a lie detection system which operates on simple and readily available equipment requiring only a computer equipped with a real time clock, a monitor, a manual data entry device such as a keyboard, a mouse or a joystick, and software to administer a questionnaire and measure reaction time.
It is another object of this invention to provide a lie detection method that can work independently of, or conjointly with, other lie detection techniques.
Further objectives and advantages of my invention will become apparent from a consideration of the drawings and the ensuing description.